Description
mixed max ( array $values )
mixed max ( mixed $value1 , mixed $value2 [, mixed $value3... ] )

If the first and only parameter is an array, max() returns the highest value in that array. If at least two parameters are provided, max() returns the biggest of these values. 

Note: PHP will evaluate a non-numeric string as 0 if compared to integer, but still return the string if it's seen as the numerically highest value. If multiple arguments evaluate to 0, max() will return a numeric 0 if given, else the alphabetical highest string value will be returned.

Parameters
An array containing the values.

Return Values
max() returns the numerically highest of the parameter values. If multiple values can be considered of the same size, the one that is listed first will be returned.

When max() is given multiple arrays, the longest array is returned. If all the arrays have the same length, max() will use lexicographic ordering to find the return value.

When given a string it will be cast as an integer when comparing.